1. Field of the Invention
The invention relates to a tool having a fixed sequence of activation steps. In particular the invention relates to medical device deployment handles that intend to eliminate practitioner errors of delivery sequence in deployment of a medical device.
2. Discussion of the Related Art
Endovascular medical devices that require a specific series of steps to complete the delivery are known in the art. For example the vascular prosthesis disclosed in U.S. Pat. No. 5,554,183 to Nazari has several control lines that are required to be activated in a particular sequence to affect proper deployment of the device. Nazari does not disclose a tool or operational handle that fail-safes the deployment sequence. Similar medical devices requiring a specific sequence of control line manipulations for proper deployment are disclosed in WO 97/48350 to Lauterjung and in U.S. Pat. No. 5,776,186 to Uflacker. Neither of these references discloses a tool or operational handle that would force the proper sequence of pull line manipulations.
There are a variety of medical device delivery handles, tools, aids, etc. used to implant endovascular devices. Examples of such delivery tools are used in steerable catheter systems, where one or more pull lines act as tendons. When pulled, the pull line deflects a portion of the catheter (normally the far distal end). The deflection of the catheter allows the precise navigation of the catheter through complex vasculature. Other medical device delivery handles provide a mechanical advantage to the pulling of a tether line or retraction sheath, used with self-expanding intravascular devices such as stent grafts. See for example U.S. Patent Application 2005/0080476 to Gunderson et al., for a handle that provides a mechanical pull advantage. Other embodiments of tools used to deliver implantable medical devices include simple luer-lock fittings that have pull lines attached to luer members. When a member is removed from the luer fitting the pull line is activated. See for example U.S. Patent Application 2002/0151953 to Chobotov et al. As typical in the art, the luer-lock and member arrangement as disclosed by Chobotov et al. are not interlocked; that is the multiple activation cords/rods can be activated in any sequence. In such non-interlocked systems, training, visual aids and labeling are typically used to encourage the proper delivery sequence. Despite the substantial efforts used to encourage the proper step sequencing, inadvertent user errors do occur.